True Duals question
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Senior User
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True Duals question
Hey yall,
I know this topic has been beat to death and i've done some reading through the posts about true duals and glasspacks. My question is i'm getting ready to run a new exhaust. It will be true duals with dual glasspacks. My big question is should i use 2 1/4 pipe and 2 1/2 glasspacks to keep my tourque or can i use 2 1/2 pipe and 3 in glasspacks? i will be running a rear exit, and i have a 351 w with hooker headers, also i will be using 11 1/2 in mini catalytic converters. any advise or opinions would be great.
Thanks everybody!
I know this topic has been beat to death and i've done some reading through the posts about true duals and glasspacks. My question is i'm getting ready to run a new exhaust. It will be true duals with dual glasspacks. My big question is should i use 2 1/4 pipe and 2 1/2 glasspacks to keep my tourque or can i use 2 1/2 pipe and 3 in glasspacks? i will be running a rear exit, and i have a 351 w with hooker headers, also i will be using 11 1/2 in mini catalytic converters. any advise or opinions would be great.
Thanks everybody!
Post Fiend
Joined: May 2006
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From: Central Florida
Scavaging action in the manifolds make torque, but a certain amount of back pressure is necissary to create scavaging action. As I just posted, I use the figure under 400hp or ci 2.5" single or 2.25" duals. The 2.5 can serve you well if you install a ballance pipe in the right location.
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From: Rio Rancho USA
And its a proven fact that the parts inside the engine are far more important to how much torque and horsepower the engine makes. Pipe just affects how its made. As long as there is plenty of room for the engine to expel exhaust gasses, the engine will make power. When the system can no longer flow what the engine needs, power will fall of.
Thats a proven fact...
Thats a proven fact...
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Joined: Aug 2006
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Here is me two cents worth on this. I had an 2001 Indian Scout. I added straight vance & hines pipes and a cam. The bike was still slugish. I had the bike dyno. The guy doing the dyno after the first run added a baffle or restrictor plate in each pipe. He said the bike needed more back pressure. Sure enough on the second run it did alot better..more HP and more Torque. So I do believe you must have back pressure to have performance. ...like I said just my two cents worth.
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Post Fiend
Joined: May 2006
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From: Central Florida
Velocity is extremely inportant. How every if cool air is being sucked up or the exhaust pulses leave a void of low pressure in the pipes, the velocity will fall off and the next pulses will have to push through it. Exhaust gasses are not alway flowing out of the motor or manifolds. They pulse, if duals do not ballance the pulses must keep up velocity while cooling, contracting and filling a volume. It's not so much the actual back pressure, but not loosing the velocity as the gasses change tempatures and have a volume to fill.
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From: Cisco, TX pop: 2500
Originally Posted by bigsexy63
Hey yall,
I know this topic has been beat to death and i've done some reading through the posts about true duals and glasspacks. My question is i'm getting ready to run a new exhaust. It will be true duals with dual glasspacks. My big question is should i use 2 1/4 pipe and 2 1/2 glasspacks to keep my tourque or can i use 2 1/2 pipe and 3 in glasspacks? i will be running a rear exit, and i have a 351 w with hooker headers, also i will be using 11 1/2 in mini catalytic converters. any advise or opinions would be great.
Thanks everybody!
I know this topic has been beat to death and i've done some reading through the posts about true duals and glasspacks. My question is i'm getting ready to run a new exhaust. It will be true duals with dual glasspacks. My big question is should i use 2 1/4 pipe and 2 1/2 glasspacks to keep my tourque or can i use 2 1/2 pipe and 3 in glasspacks? i will be running a rear exit, and i have a 351 w with hooker headers, also i will be using 11 1/2 in mini catalytic converters. any advise or opinions would be great.
Thanks everybody!
Elder User
Joined: Mar 2006
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If its basicaly a stock 351w go with 2 1/4 to keep from loosing bottom end. If its modded with a cam and higher compression etc then you can do 2 1/2. Ive seen the debate going on here about if pipe size will have an effect on power and the power range and it does. My dad has been installing custom exhaust systems for 30 years as we have an auto repair shop and a pipe bender. Ill give an example, had a customer come in with a chevy pickup, 350 motor stock, insisted he wanted 2 1/2 true duals despite my dad recomending 2 1/4. Well a week later he was back saying he lost all his low end pulling power and was having trouble pulling his trailer now. Switched the exhaust to 2 1/4 and it ran great and regained all its low end torque. I could do more examples but i dont ill change anyones opinion and dont want to debate this forever. just trying to help with what i have seen.
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thanks smallblock351w,
i'll be using the 2 1/4 pipe two mini cats and 2 1/2 glasspacks, then the tips,do u have any ideas on what length glasspack i know i want a deeper sound, so i'm thinking longer ones.
i'll be using the 2 1/4 pipe two mini cats and 2 1/2 glasspacks, then the tips,do u have any ideas on what length glasspack i know i want a deeper sound, so i'm thinking longer ones.